Amino acids contain an amino group (-NH2) and a carboxyl group (-COOH) in the molecular structure, and both the amino group and the carboxyl group are organic compounds directly bonded to a -CH-structure. Amino acids are the basic units that make up the protein. Before answering how many amino acids are there, we should know that amino acids differ from each other by amino group and carboxyl group.

How many amino acids are there?

There are nearly 300 amico acids existing in nature.

20 natural amino acids are the main units that make up the protein in the living body. Another 2 kinds of amino acid, which are selenocysteine and pyrrolysine, are newly found in a few proteins. They are both naturally occurring amino acids, and 8 of the 20 standard amino acids are essential to human body.

How many essential amino acids are there?

The essential amino acids mean that these amino acids have to be taken in from foods because human body cannot produce these amino acids on its own. There are 8 essential amino acids, which are lysine, tryptophan, phenylalanine, methionine, threonine, isoleucine, leucine, and valine.

The 10 nonessential amino acids refer to those amino acids that the body can make on its own, like glycine, alanine and others. The semi-essential amino acids are those that have to be taken in under certain circumstances. There are only 2 of them, arginine and histidine.

What’s the use of essential amino acids?

Essential amino acids are often used in food industry, pharmaceutical industry and personal care industry.

In food industry, amino acids are used as nutrition enhancer, raw materials of sweetener and flavour enhancer .

• Lysine, methionine, tryptophan and arginine, are commonly used as nutrition enhancers. Lysine, methionine, tryptophan are the essntial amino acids which cannot be produced by human body. Arginine is an essential amino acid for the growth and development of children.
• One of the most used sweetener, aspartame, is synthesized from aspartic acid and phenylalanine. Aspartame is 200 times as sweet as sucrose, and suitable for diabetic patients. Aspartame is often used in beverage, candy, bread, ect.
• Monosodium Glutamate(MSG) is the most widely used salts of amino acids. Glutamic acid has sour flavor. After the formation of glutamate sodium salt, the sour flavor disappears and the flavor enhances. Monosodium glutamate is currently the most widely used flavor agent .

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